Method for producing a yarn having latent bulking characteristics

ABSTRACT

A method for producing a yarn having latent bulking characteristics and the apparatus therefor is described. The yarn is composed of multifilament synthetic fibers which have been crimped and subjected to a constant tensioning process. The process involves subjecting a drawn yarn, preferably freshly drawn, to a crimping process which can be any of a number of crimping methods including stuffer box crimping, gear crimping, steam jet crimping and the like. The yarn is withdrawn from the crimping step under a low, substantially uniform tension, tensioning the yarn under a higher constant tension to at least partially extend the crimps, entangling or twisting the yarn and taking the yarn up on a package. The bulk characteristics of the yarn are preferably developed after incorporation into the end product such as a carpet by subjecting to heat and moisture.

Binlord et al.

States atent' 191 [54] METHOD FOR PRODUCING A YARN HAVlNG LATENT BULKINGCHARACTERlSTlCS [75] Inventors: Jack C. Binlord; Frederick A.

Etlhridge; James R. Talbot, all of Charlotte, NC.

[73] Assignee: Fiber Industries, lnc., Charlotte,

[22] Filed: Nov. 11, 119711 [21] App1.No.: 194,597

Related 1.1.8. Application Data [62] Division of Ser. No. 848,549, Aug.8, 1969, Pat. No.

[52] US. Cl. 28/72.l4, 28/72.14 [51] llnt. Cl D02g l/l2, D02g 1/14 [58]Field of Search 28/1.3, 72.11, 1.8, 1.6, 28/7214, 72.12, 72.15

[56] References Cited UNlTED STATES PATENTS 3,022,545 2/1962 Wylde et a128/1.8 3,027,619 4/1962 List et a1 28/72.14 X 3,143,784 8/1964 Scott28/72.12 3,200,466 8/1965 Duga et a1. 3,280,444 10/1966 Stanley 28/72.143,399,108 8/1968 Olson 28/72.11 X 3,417,445 12/1968 Gemeinhart et a1.28/1.3 X 3,500,518 3/1970 Stanley et a1. 28/72.14 X 3,501,819 3/1970Satterwhite 28/72.11 X 3,570,083 3/1971 Stanley 28/72.14 X

f I lo 0 COMPACTI NG MEANS PACKAGING Aug. 27, 1974 3,570,084 3/1971Stanley et a1. 28/72. 14 3,601,872 8/1971 Potman 28/72.l1 X 3,605,3939/1971 Schroeder 28/72.l1 X 3,611,522 10/1971 Daniels et a1. 28/72.113,703,753 11/1972 Binford et a1 28/72.12

FOREIGN PATENTS OR APPLICATIONS 1,064,765 4/1967 Great Britain 28/72.l 1

Primary Examinerbouis K. Rimrodt Attorney, Agent, or Firm-LouisGubinsky; Pamela D. Kasa [57] ABSTRACT A method for producing a yarnhaving latent bulking characteristics and the apparatus therefor isdescribed. The yarn is composed of multifilament synthetic fibers whichhave been crimped and subjected to a constant tensioning process. Theprocess involves subjecting a drawn yarn, preferably freshly drawn, to acrimping process which can be any of a number of crimping methodsincluding stuffer box crimping, gear crimp- 16 Claims, 7 Drawing FiguresPAIENIEDAIIEZYW J 3.831.231 M2673 I 1 a 1 E as y f XTRKQ YARN DIRECTIONH64 FIG 5PRIOR ART METHOD FOR PRODUCING A YARN HAVING LATENT BULKINGCHARACTERISTICS This is a divisional application of Ser. No. 848,549,filed Aug. 8, 1969, now U.S. Pat. No. 3,654,677, granted Apr. 11, 1972.

BACKGROUND OF THE INVENTION This invention relates to production of acrimped yarn which has latent bulking characteristics and moreparticularly to the production of a crimped yarn under conditions whichlead to improved uniformity of bulking characteristics and dyeability inthe end product. In particular, the invention is directed to carpetyarns, and more particularly, nylon carpet yarns, although other yarnsand other uses are also contemplated as will be evident from thedescriptions set forth herein.

Numerous methods have been proposed for the production of crimped yarns.Many of these processes provide useful yarns which can be used in manyapplications without difficulty. However, in the production of carpetyarns and certain fabric yarns wherein a great number of yarn ends oryarn packages go into a single strip of carpet or fabric, the uniformityfrom package to package and from end to end must be extremely good inorder to provide a yarn which is useful for the piece dyeing of the endproduct. Yarns which do not have the required uniformity have to bepackage dyed and the yarn shades matched to obtain the desireduniformity or space dyed prior to producing the end prodnot. Because itis more preferred in most instances to produce the end product, such asa carpet, and then dye the end product in its entirety, yarns which donot have the required degree of uniformity are considered to be ofreduced value.

It is therefore an object of the present invention to provide a methodfor reducing, and in many instances eliminating, yarn imperfections byreducing yarn tension variations to a minimum. It is another object ofthe present invention to provide a method for closely controlling theprocess history of the yarn from the drawing step through the crimpingand final packaging of the yarn, thereby controlling the tensionsapplied to the yarn in a manner whereby tension fluctuations aremaintained at an absolute minimum. It is a further object of the presentinvention to provide an apparatus for the application of tensions to theyarn and a total process apparatus for applying and controlling thehistory of yarn tensions from the drawing step through the packaging ofthe crimped yarn. These and other objects will become apparent to thoseskilled in the art from the description which follows.

THE INVENTION In accordance with the invention, a process is providedfor producing a crimped yarn having latent bulking characteristicscomprising feeding a drawn, pretensioned, multifilament yarn to acrimping zone, crimping said yarn, withdrawing crimped yarn from saidcrimping zone under a low, substantially constant tension and at asubstantially uniform speed, cooling said yarn, increasing the tensionon said yarn to a substantially constant tension between 0.03 to 0.8grams per denier to at least partially reduce the amplitude of saidcrimps and compacting said yarn to facilitate further processing.

In accordance with a further aspect of the invention, an apparatus isprovided for treating said yarn comprising yarn drawing means, yarncrimping means, yarn tensioning means and yarn compacting means, saidmeans being consecutively, operatively connected, said yarn drawingmeans comprising a feed roll and a draw roll having a draw pin positiontherebetween to draw yarn, said crimping means being positioned inrelationship to said drawing means for the receipt with a minimum delayof freshly drawn yarn, said yarn tensioning means being positioned forthe receipt of freshly crimped yarn from said crimping means and for theapplication of tension to said yarn thereby increasing the force of yarncontact with further yarn tensioning means, said yarn further tensioningmeans comprising a braked wheel and a withdrawal roll havingthereinbetween a tension leveler wherein the yarn is passed from saidbraked wheel across said tension leveler through said withdrawal roll tosaid compacting means.

DETAILS OF THE INVENTION The invention will be described more clearly byreference to the drawings wherein:

FIG. I is a schematic flow sheet. representing a preferred embodiment ofthe present invention;

FIG. 2 is an enlarged sectional view of a preferred pretensioning jetillustrated in FIG. 1;

FIG. 3 is a sectional view along line 33 of FIG. 2 further illustratinga preferred tensioning jet;

FIG. 4 is a tension trace indicating the recorded tensions of runningyarn in accordance with the present constant tensioning process;

FIG. 5 is a tension trace of recorded tensions of yarns in accordancewith the prior art constant elongation stretch method;

FIG. 6 is a cross section of a steam bulking jet suitable for use as thecrimping means of the invention; and

FIG. 7 is a cross section of a pair of gear crimper wheels suitable foruse as the crimping means of this invention.

Referring to FIG. I, yarn I0 is drawn from one or more packages 12 toproduce the yarn of the desired total denier by nip rolls 14. Yarn 1.0then proceeds to feed roll 16 and across draw pin 18 to draw roll 20.Draw roll 20 operates at a higher linear speed than feed roll 16,thereby effecting a drawing of the yarn at pin 18 in the desired drawratio. Such ratio is determined by the relative roll speeds which areselected in accordance with the particular yarns being treated and theparticular properties desired in the drawn yarn. Normally the draw ratiois between about 3:1 to 6:1, while the nylon 6,6, a draw ratio of about3.5:1 to 45:1 is preferred.

Yarn I0 proceeds from the drawing means through the crimping means whichcan be any of a number of well known crimping means including a steamjet bulking means such as is described in U.S. Pat. No. 3,380,242,stuffer box crimping means, particularly utilizing a stuffer box crimperof the type described in copending application Ser. No. 848,495, filedAug. 8, 1969, now U.S. Pat. No. 3,605,221, granted Sept. 20, 1971entitled Stuffer Box Crimper and Method Therefor in the name of JackBi'nford et al., commonly assigned to the same assignee as the presentapplication and filed on even date herewith, which application is herebyincorporated by reference into this application. A further method ofcrimping which can be used is by means of intermeshing geared wheelswhich crimp the yarn thereinbetween as is well known in the art.

The preferred method of crimping is by stuffer box crimping whereincrimping rolls 22 feed yarn 10 into stuffer box 24 thereby setting thecrimps into the yarn. Crimped yarn 10 is preferably extruded fromstuffer box 24 or otherwise extracted under a low tension of to 0.05grams per denier and passed through quenching and pretensioning means 26which causes a tension increase on the yarn by impeding yarn travel andenables the yarn to make low slippage contact with braked roll 28.Braking action in roll 28 restrains the rotation thereof relative towithdrawal roll 34 and provides a further increase in yarn tension tothe desired 0.03 to 0.8 grams per denier level which is below thedrawing force of the yarn. Alternative pretension means 26 can includenip rolls or other holding means which impede the forward motion of theyarn sufficiently to engage the yarn against braked roll 28. Thus, yarntravels from braked roll 28 across idler roll 30 and tension leveler 32to withdrawal roll 34 the latter of which exerts a pulling force on theyarn to the desired tension level, which level is below the drawingforce of the yarn.

A particularly significant aspect of the present invention resides inthe maintenance of a substantially constant pretension, draw tension,crimp amplitude reduction tension and windup tension which is notallowed to vary significantly even with fluctuations in the feed of yarnbetween braked roll 28 and withdrawal rolls 34. Thus tension leveller 32is preferably a spring loaded movably mounted means which varies thedistance between braked roll 28 and withdrawal roll 34, thereby keepingthe tension substantially constant. Suitable tension leveler meansinclude spring loaded dancer arms, reciprocal spring mounted rollers orthe like means, e.g. tension controlled roll speeds, of leveling out anapplied tension.

From withdrawal roll 34, the yarn proceeds through compacting means 36coupled with a preferred relaxation of the yarn in the range of l to 10percent of the applied stretch. The compacting means utilized includeconventional twisting or twist substitutes including air entanglement orthe application of an adhesive material. From the compacting means 36,yarn 10 is passed through feed rolls 38 to packaging 40 or directly tothe end use.

Referring more particularly to the more specific preferred embodimentsof the present invention, it is often preferred to have a slightlyoverfeed of yarn between draw roll and the crimping means such as in therange of 0.1 to about 3 percent. Such a small degree of overfeed hasbeen found to be particularly advantageous in the development of crimpwhich produces a particularly desirable bloom in the end product.

The crimping means utilized preferably extrudes the crimped fibers undersubstantially zero tension or a very low tension, e.g. O to 0.05 gramsper denier and more preferably 0 to 0.01 grams per denier. It has beenfound that the application in any greater amount of tension, such aswould be required to actually pull the yarn from the crimping means,introduces variations into the yarn which subsequently shows up in thebulking properties of the yarn and/or the dyeability thereof as streaks,worms or other undesirable imperfections.

This is believed to occur because of the periodic or sporadicrequirement of increased tensions to extract such yarns. Therefore, theextrusion of the yarn from the crimping means is under tensions which donot exceed 0.05 grams per denier.

Normally, yarn coming from the crimping zone is in a heated conditioneither because of the application of heat in the setting of the yarn orthe heat of friction developed in the crimping process or other addedheat. Thus, temperatures of about 40 to 180 Centigrade or higher arepreferably developed in the crimping zone, depending on the particularcrimping process. The higher temperatures are normally used with steamjet crimping and the lower temperatures with stuffer box and gearcrimping means. As such, it is preferred to quench the yarn as itcomesout of the crimping means.

A particularly desirable manner of quenching the yarn while at the sametime applying the initial pretensioning to the yarn is accomplished bythe apparatus illustrated in FIGS. 2 and 3. Because the yarn exitingfrom the crimping area preferably is under a very low tension, apretension is preferably applied so as to aid in the further processingof the yarns in the subsequent tensioning step. As such, quenching jet42 is preferably utilized. Quenching jet 42 utilizes two opposedsidewalls 44 having in each wall a plenum chamber 46 for thedistribution of pressurized gas to exit ports 48. Exit ports 48preferably are slots or a plurality of holes or a combination thereof,which are preferably positioned in a parallel relationship with respectto each other. Exit ports 48 are aimed at the opposing wall of thequench jet in an angled relationship to sidewall 44 and the line of yarntravel. As yarn is passed through the gaseous jet stream, the gasimpinges against the yarn thereby inhibiting the forward motion of theyarn and creating a tension on the yarn exiting from the jet area. Toestablish the desired tension, it is preferred to have the jets aimed atan angle of of about 5 to with respect to sidewall 44 or running line ofthe yarn, and more preferably 5 to 45 thereby exerting the desired backpressure and pretensioning of the yarn as the yarn passes therethrough.Thus, the quenching jet accomplishes both the cooling of the yarn andthe pretensioning thereof in an amount of 0.003 to about 0.06 grams perdenier and more preferably 0.005 to 0.03 grams per denier. Because ofthe desire to cool the yarn, any nonreactive gas can be used, with airbeing preferred. Special cooling of the air is normally not required.Thus ambient gas temperatures are generally quite suitable.

While the exit ports can be so arranged to induce a twisting action inthe yarn, it is preferred that the exit ports are positioned to avoid atwisting effect. The amount of tension applied to the yarn in thepretensioning is controlled by controlling the gas pressure, the angleat which the gas impinges against the yarn, the gas flow rate, thepositioning of the sidewalls, and the like. Further, it is desirable toeffect at least some entanglement of the yarn so as to aid in thefurther processing of the yarn by containing broken or projectedfilaments. The described apparatus readily accomplishes this,particularly at the preferred gas impingement angles and back pressureproducing velocities.

The particular gas used in the quenching jet is preferably air, but canbe any cooling gas such as nitrogen, various inert gases and the like asis well known to those skilled in the art. The gas pressure utilized isdependent upon the number of exit ports used, the shape thereof, thecross-sectional area and the desired degree of pretensioning. Thus, itis preferred to adjust the air pressure in accordance with the desiredpretensioning.

Brake wheel 28 can be a number of different known braking wheels such asfrictionally impeded channeled wheels. A particularly preferred brakeclutch is a magnetic particle clutch in which the braking tension can bereadily adjusted to correspond to the subsequently applied tensioning.Other means of frictional braking such as fluid clutches, eddy currentbraking and the like are used with correspondingly good results.

Between brake roll 28 and withdrawal roll 34, a substantial constanttension is applied to the moving yarn. This tension is below the tensionrequired to draw the yarn, but is sufficient to partially remove thecrimps in the yarn by reducing their amplitude without permanentlyremoving the crimp. Such stretching takes the crimps out of registrywith each other and induces a latent effect to the crimp which enableseasier fabrica tion of the end product with the yarn as well asimproving the development of bulkiness in the end product. Thus, theamount of stretch applied is in the range of about 0.03 to 0.8 grams perdenier and more preferably about 0.05 to 0.5 grams per denier. Tensionleveler 32 is adjusted for the applied tension to smooth out tensionvariations as may occur due to periodic sporadic variations in the feedof the yarn across brake roll 28.

F IG. 6 shows in cross section a jet which can be used as the crimpingmeans of the invention when it is desired to produce a steam jet crimpedor bulked yarn. The jet unit comprises a T-piece 11, the double limb 12of which communicates at each end with the atmosphere, while the thirdlimb 13 is connected to a steam header for the supply of steam to theunit. Within the double limb 12 is slipped a cylindrical member 15 whichis circumferentially grooved about one-quarter and three-quarters wayalong its length for the reception of rings 16 of suitable packingmaterial adapted to make a tight joint against the wall of the doublelimb. lnto one end of the cylindrical member is slipped a tubular yarninlet member 17, the tip 18 of which is of double-conical form, havingconical angles of 47 near the tip and 33a short distance behind the tip.The inlet has an entry bore 19 of one-eighth inch, which tapers to onethirty-second inch at the tip. At the other end of the cylindricalmember 15 is inserted a venturi tube 20 having an inlet cone 21 of 40angle, a throat diameter 22 of one-sixteenth inch, and an outlet cone 23of angle, the tip 18 of the inlet jet entering into the inlet cone 21 ofthe venturi. Both the inlet jet 17 and the venturi tube 20 areexternally flanged to engage against the ends of the cylindrical memberand are held in place by two collars 24, 25 internally flanged to engageover the external flanges of the inlet jet l7 and venturi respectively,and internally screw-threaded to screw over the cylindrical member 15.The inner edges of the collars 24, engage the packing rings 16 andcompress them against the wall of the double limb 12 of the T-piece 11,so holding the whole assembly in place. Mid-way along its length thecylindrical member 15 is bored with diametrically opposite holes 26 forthe admission of steam entering from the steam main 14 through the thirdlimb 13 of the T-piece 11. A gauze collar 27 may be provided surroundingthe middle portion of the cylindrical member 15.

FIG. 7 illustrates a gear crimper comprised of rotatable wheels 5, 6,each carrying a plurality of teeth illus trated individually by 7, 5, tocrimp yarn 3 passing therebetween.

FIG. 1- represents a tension trace showing the substantially constanttension applied by the present method in the area between idler roll 30and tension leveler 32. FIG. 5 represents a tension trace showing thefluctuations in tension as occur in the prior art constant elongationstretching process.

The particular yarn treated by the present process can be any of thesynthetic continuous filament yarn including nylon, polyester, acrylic,modacrylic, polypropylene, polyvinyl chloride, polyvinylidene chlorides,Darvan, Spandex, and the like as are well known in the art. Theparticular fiber denier can be any fiber denier within the range ofabout 0.5 to 200 denier per filament but particularly those in thetextile range of about 0.5 to 10 denier per filament and those in theindustrial and carpet yarn range of about 8 to 30 denier per filament.Accordingly, the total yarn denier can vary substantially depending uponthe particular use to which the processed yarn is to be put. Carpet yarntotal deniers are in the range of about 700 to about 5000, morepreferably about 800 to 4000 total denier. Textile yarns mayconveniently have lower total denier ranges such as from about 100 to800. Of course, greater and lesser total denier yarns can be readilyprocessed, but the best applications are effected in the production ofcarpet yarns which are particularly sensitive to texturing variations.

The invention will be described more particularly with reference to thefollowing example which illustrates certain preferred embodiments of thepresent invention.

EXAMPLE Nylon 6,6, polyhexamethylene adipamide fiber, was processed inaccordance with the present invention and particularly in accordance tothe schematic shown in FIG. 1 of the drawing and the apparatusesillustrated therein. Undrawn yarn was fed to a drawing means comprisinga pin and draw roll wherein it was drawn at the rate of 1,620 feet perminute at a total draw ratio of 3.82. The freshly drawn yarn wasdirectly fed to a stuffer box crimper at a feed input of l,6l3 feet perminute to the crimper rolls. The stuffer box crimper utilized was thatdescribed in US. Pat. No. 3,605,221.

A crimped yarn of generally saw-tooth crimps at a temperature of about80 centigrade exited under zero tension from the stuffer box and waspassed through the quenching jet of FIGS. 2 and 3 which was operated atan air pressure of 30 pounds per square inch gauge. The angle ofimpingement of the gas jet stream against the yarn formed an angle of 30between the yarn and the axes of the jet exit port. This pressue andangle of impingement applied a tension of 50 to grams of tension to theyarn, which tension equaled about 0.019 to 0.029 grams per denier. Thepre'tensioned yarn from the quench jet engaged a magnetically brakedparticle clutch and traveled across a spring loaded dancer arm to awithdrawal roll which applied a 400 gram tension to the running yarnbetween the clutch roll and the stretch roll. This tension equaled about0.154 grams per denier. The consistency of the tension is illustrated inFIG. 4.

From withdrawal rolls 34, the yarn was relaxed percent of the tensionedlength and passed through a yarn entangling jet. The yarn was then woundon a package as a 2,600/136 nylon 66 carpet yarn. This yarn had a skeinlength of about 14 /2 inches and about 15 to 19 crimps per inch. Theskein length was measured with meter length raps and subsequentlysubmerged in 60 centigrade water for three minutes prior to determiningthe length.

The yarn produced in accordance with this method was made into acontinuous filament carpet and piece dyed. Examination of the piece dyedproduct indicated that it was substantially free of bulk and dyevariations. This is indicative of package to package uniformity of theyarn as well as within package uniformity.

The yarn produced could be varied in the number of crimps per inch andthe skein length of the resulting yarn. Using a stuffer box crimper, agenerally saw tooth crimp of primary and secondary crimp amplitudes isproduced in the yarn. The number of crimps per inch can be adjustedbetween about 3 to 30 crimps per inch or more while about 5 to 20 crimpsper inch is generally most preferred. Also, the skein length of thecrimped yarn can be varied from about inches to about 19 inches as maybe desired in the particular end use by changes in the crimpingtemperature, the after tension and the like adjustments. The preferredrange for carpet yarns of this type is a skein length of about 1 l toinches.

In the same manner, other crimping processes such as gear crimping orsteam jet bulking are substituted for stuffer box crimping wherebysimilar results are obtained. The particular type of crimp is variedwith the particular crimping method utilized.

While the invention has been described more particularly with respect tonylon, correspondingly good results are obtained with the otherenumerated synthetic continuous filaments. Also, filaments of greaterand lesser total denier and denier per filaments can be processedaccordingly with correspondingly good results.

What is claimed is:

l. A process for producing a crimped yarn having la tent bulkingcharacteristics which comprises feeding a multifilament yarn to acrimping zone, crimping the yarn in the crimping zone, withdrawing theyarn in crimped form from the crimping zone under a low substantiallycontstant pretension increasing the tension 8 on the crimpedpretensioned yarn to a constant crimp amplitude reduction tensionimmediately after withdrawal of the yarn from the pretensioning zoneprior to the application of any yarn treating or processing means to theyarn and controlling the speed of said yarn being subjected to saidconstant tensions.

2. The process of claim 1 wherein the tensioning includes apretensioning of about 0.003 to 0.05 grams per denier and a subsequentfurther tensioning to between 0.05 to 0.8 grams per denier.

3. The process of claim l wherein a constant crimp amplitude reductiontension of between 0.03 and 0.8 grams per denier is applied to the yarn.

4. The process of claim 3 including the additional step of compactingthe yarn after the application of the constant crimp amplitude reductiontension.

5. The process of claim 4 wherein the compacting after tensioning is byentanglement by subjecting said yarn to pressurized gas impingementwhile in a confined zone.

6. The process of claim 4 wherein the compacting is by twisting.

7. The process of claim 4 wherein the compacting of the yarn is effectedwhile relaxing said tensioned yarn l to 10 percent.

8. The process of claim 1 wherein the yarn is continuous filament carpetyarn.

9. The process of claim 8 wherein the yarn is polyamide.

10. The process of claim 1 where the tension on the yarn being withdrawnfrom the crimping zone is less than about 0.01 grams per denier.

11. The process of claim 1 wherein the crimping is effected by stufferbox crimping.

12. The process of claim ll wherein the crimping is effected by gearcrimping.

13. The process of claim 1 wherein the yarn is drawn and thenimmediately fed to the crimping zone.

14. The process of claim 1 wherein at least a portion of the constanttension applied to the yarn is applied by impingement of a pressurized,yarn cooling gas against the yarn.

15. The process of claim 14 wherein the pressurized gas further effectsan entanglement of the yarn.

16. The process of claim l4 wherein the impingement of the pressurizedgas is at an angle of about 5 to against the direction of the runningline of the yarn to thereby pretension the yarn.

l l i

1. A process for producing a crimped yarn having latent bulkingcharacteristics which comprises feeding a multifilament yarn to acrimping zone, crimping the yarn in the crimping zone, withdrawing theyarn in crimped form from the crimping zone under a low substantiallycontstant pretension increasing the tension on the crimped pretensionedyarn to a constant crimp amplitude reduction tension immediately afterwithdrawal of the yarn from the pretensioning zone prior to theapplication of any yarn treating or processing means to the yarn andcontrolling the speed of said yarn being subjected to said constanttensions.
 2. The process of claim 1 wherein the tensioning includes apretensioning of about 0.003 to 0.05 grams per denier and a subsequentfurther tensioning to between 0.05 to 0.8 grams per denier.
 3. Theprocess of claim 1 wherein a constant crimp amplitude reduction tensionof between 0.03 and 0.8 grams per denier is applied to the yarn.
 4. Theprocess of claim 3 including the additional step of compacting the yarnafter the application of the constant crimp amplitude reduction tension.5. The process of claim 4 wherein the compacting after tensioning is byentanglement by subjecting said yarn to pressurized gas impingementwhile in a confined zone.
 6. The process of claim 4 wherein thecompacting is by twisting.
 7. The process of claim 4 wherein thecompacting of the yarn is effected while relaxing said tensioned yarn 1to 10 percent.
 8. The process of claim 1 wherein the yarn is continuousfilament carpet yarn.
 9. The process of claim 8 wherein the yarn ispolyamide.
 10. The process of claim 1 where the tension on the yarnbeing withdrawn from the crimping zone is less than about 0.01 grams perdenier.
 11. The process of claim 1 wherein the crimping is effected bystuffer box crimping.
 12. The process of claim 1 wherein the crimping iseffected by gear crimping.
 13. The process of claim 1 wherein the yarnis drawn and then immediately fed to the crimping zone.
 14. The processof claim 1 wherein at least a portion of the constant tension applied tothe yarn is applied by impingement of a pressurized, yarn cooling gasagainst the yarn.
 15. The process of claim 14 wherein the pressurizedgas further effects an entanglement of the yarn.
 16. The process ofclaim 14 wherein the impingement of the pressurized gas is at an angleof about 5 to 70* against the direction of the running line of the yarnto thereby pretension the yarn.